What kind of a guy makes a living by beating the crap out of other men?

A crazy guy, pure and simple.

And that’s the problem, says Quebec-born mixed martial arts legend Georges St-Pierre. He’s the best at what he does, but what he does was starting to drive him nuts.

"When you're the champion, you're like the target. Everybody challenging you all the time, and you have a lot of critics, a lot of expectation," said St-Pierre during interviews in Toronto this week to promote Takedown: The DNA of GSP, a documentary that follows his rise in the UFC and his comeback after a potentially career-ending knee injury that sidelined him for most of 2012. Takedown opens Thursday in limited release.

But it was after the cameras stopped rolling that the former welterweight champion decided to take a hiatus from the UFC, something he’d been mulling as far back as late 2010.

"I started thinking about stepping away when I fought (UFC welterweight championship contender Josh) Koscheck, before my injury, because I see the things going on, what is happening in the sport," St-Pierre said.

"I stopped because my mental health was in jeopardy. I felt it coming, I said, 'You know what, it’s too much, I’m going crazy, before I do something crazy I’m going to stop, take a break, step out of it.'"

St-Pierre frequently refers to his obsessive-compulsive tendencies – he touches on it in Takedown as well, saying he can’t step on sidewalk cracks unless he does so with both feet – and the double-edged sword it wields.

"The fun became a business, and then the business became a lot of critics, expectations, the pressure – plus my obsessive-compulsive problem I have, which is good when you’re an athlete, but in real life it’s bad, it can make you go crazy, it can make you lose your mental health," said St-Pierre. "And that’s what was going to happen to me."

Born in the tiny town of Saint-Isidore, Que., St-Pierre is as well-known for his humility, positive attitude and sportsmanship as he is for his dominance in the Octagon, including an unprecedented 12 consecutive victories that culminated with his controversial split decision win against Johny Hendricks last November.

But for now he’s taking it easy, sleeping better and supporting his teammates in their bouts. There’s been no word if or when he might return to the UFC, but he may not need to, if his second career takes off. After Takedown, St-Pierre’s next appearance on the big screen will be in this spring's Captain America: The Winter Soldier, playing the classic villain Batroc the Leaper.

"I really enjoyed it, it was a new experience for me and I had a lot of fun," St-Pierre said of the movie, which has him squaring off against Chris Evans' star-spangled superhero.

"I play a French mercenary who's a martial artist and also an Olympic lifter and world champion," said St-Pierre. "I'm very strong, but I'm a bad guy, I'm not a good guy. It was fun."